i dont think villain has KQ here, and a set is unlikely as well if he is a true donk. A bad player i think would either slowplay the hell out of a set or KQ on this flop or probably 4bet minraise the flop or at least make a small reraise to keep hero involved in hand. I dont see many bad players taking a line like this, especially when he check calls turn. If he has KQ, sucks for hero, but if he's playing like that, you will probably get it back soon enough.

*after viewing results, seems A10 seems like a perfect hand for villain to have. He probably thought he had the best hand on the flop and just wanted to see how things deceloped on the turn and river and once no scare cards hit (K,Q, spade), he figured his hand was still good and could get a call from AK/AQ i guess